Sensitivity to training system parameters and soil surface albedo of solar radiation intercepted by vine rows

Abstract

A geometrical model for solar radiation interception has already been developed and validated for application in vine training systems where each row is composed of only one vertical foliage plane. This model has been successfully used for simplified estimation of daily transpiration of non-stressed vines (RIOU et al. 1994) and in models of photosynthesis. It may therefore also be used for long-term estimation of the soil water balance and growth, which considerably influence grape quality.
In this paper, using simulations based on the model, we studied changes of the solar radiation interception ratio and the vineyard albedo with row distance, row azimuth, shape of rows, and soil surface albedo.
The model was applied to different training systems with a single vertical plane of foliage, in conjunction with 10-day means of incoming global solar radiation for an average year in Bordeaux. From mid-April through end of September values of the ratio of intercepted radiation and of the absolute value of solar radiation interception by the rows were highly sensitive to the view factor of a row with its neighbour. Simplified expressions were established in order to summarize a large number of simulations by the model. These expressions allow an easy assessment of the sensitivity to training system parameters at that latitude. Within a realistic range of variation and ranked in a hierarchical order, most significant parameters for the solar radiation interception ratio and the absolute value of solar radiation interception by the rows were relative spacing of the rows, shape of the rows, soil surface albedo and row azimuth.